1. Field
The invention relates to internal combustion engines which are designed to operate on gaseous hydrogen fuel and which utilize a fuel tank containing a metal hydride for the storage of hydrogen. In particular, the invention relates to a fuel system for conveying the fuel from the storage tanks to the engine.
2. State of the Art
Internal combustion engines utilizing hydrogen fuel have been shown to be both feasible and an attractive alternative to engines which utilize gasoline. See, for example, U.S. Pat. No. 3,983,882 issued on Oct. 5, 1976 to Roger E. Billings, as well as the references cited therein. The storage of hydrogen for use in internal combustion engines has presented difficult problems. However, the use of storage containers containing metal hydrides has mitigated many of those problems. See, for example, U.S. Pat. No. 4,016,836 issued on Apr. 12, 1977 to Donald B. MacKay et al.
The hydride-containing containers are typically charged with hydrogen at a pressure of about 500 psig or greater. This pressure must be regulated when the stored hydrogen is fed to the mixing device on the engine which mixes the hydrogen with air and introduces the mixture to the intake manifold of the engine. Regulators have been used in prior hydrogen fuel systems, wherein the regulator regulates the hydrogen pressure downstream therefrom at a present pressure. As the hydrogen is used from the hydride-containing storage tanks, the pressure of the hydrogen released by the hydride is continuously reduced. At a point wherein the pressure of the hydrogen coming from the storage tanks is less than the preset pressure at which the regulator is set, the regulator becomes ineffective, and the pressure downstream therefrom is the pressure of the hydrogen coming from the storage tanks less the pressure drop incurred in passing through the flow conduits and the pressure regulator. Because of the relatively large pressure drop incurred, the hydride-storage tanks required recharging when the pressure therein fell to about 100 to 150 psig. Considerable hydrogen is still contained in the storage tanks at that pressure but is unavailable because of the pressure drop incurred in delivering the hydrogen to the engine.
3. Objective:
The principal objective of the present invention was to provide a hydrogen fuel supply system in which nearly all the hydrogen stored in the storage tank before the tank has to be recharged.